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Add fixture/snapshot tests
Add tests that transform vendored API responses (fixtures) into vendored /metrics output (snapshots), so that we can see how changes to the exporter implementation affect the actual output of the exporter, in the form of changes to the snapshots. I've sourced the fixtures from debug JSON logging of real API responses from tasks running in AWS. Each task consisted of an ecs_exporter container and a prometheus container. My expectation is that fixtures should not be updated unless we become informed that API responses have materially changed, e.g. because new features we are using were added, or breaking changes have been made. I've got two sets of fixtures and snapshots, one for EC2 and one for Fargate. The API responses differ between EC2 and Fargate enough (because, among other things, they use two completely different implementations of the task metadata API, and two different container runtimes entirely!) that I think it's worth covering them both independently. Closes #99. Signed-off-by: Ian Kerins <[email protected]>
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Diff for: ‎README.md

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## Example output
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(With `--web.disable-exporter-metrics` passed, such that standard Go metrics are not included here.)
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```
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# HELP ecs_container_cpu_usage_seconds_total Cumulative total container CPU usage in seconds.
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# TYPE ecs_container_cpu_usage_seconds_total counter
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ecs_container_cpu_usage_seconds_total{container_name="ecs-exporter"} 0.028057878
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# HELP ecs_container_memory_limit_bytes Configured container memory limit in bytes, set from the container-level limit in the task definition if any, otherwise the task-level limit.
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# TYPE ecs_container_memory_limit_bytes gauge
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ecs_container_memory_limit_bytes{container_name="ecs-exporter"} 5.36870912e+08
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# HELP ecs_container_memory_page_cache_size_bytes Current container memory page cache size in bytes. This is not a subset of used bytes.
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# TYPE ecs_container_memory_page_cache_size_bytes gauge
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ecs_container_memory_page_cache_size_bytes{container_name="ecs-exporter"} 0
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# HELP ecs_container_memory_usage_bytes Current container memory usage in bytes.
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# TYPE ecs_container_memory_usage_bytes gauge
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ecs_container_memory_usage_bytes{container_name="ecs-exporter"} 4.243456e+06
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# HELP ecs_exporter_build_info A metric with a constant '1' value labeled by version, revision, branch, goversion from which ecs_exporter was built, and the goos and goarch for the build.
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# TYPE ecs_exporter_build_info gauge
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ecs_exporter_build_info{branch="",goarch="arm64",goos="linux",goversion="go1.23.2",revision="unknown",tags="unknown",version=""} 1
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# HELP ecs_network_receive_bytes_total Cumulative total size of network packets received in bytes.
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# TYPE ecs_network_receive_bytes_total counter
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ecs_network_receive_bytes_total{interface="eth1"} 1.1172419e+07
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# HELP ecs_network_receive_errors_total Cumulative total count of network errors in receiving.
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# TYPE ecs_network_receive_errors_total counter
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ecs_network_receive_errors_total{interface="eth1"} 0
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# HELP ecs_network_receive_packets_dropped_total Cumulative total count of network packets dropped in receiving.
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# TYPE ecs_network_receive_packets_dropped_total counter
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ecs_network_receive_packets_dropped_total{interface="eth1"} 0
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# HELP ecs_network_receive_packets_total Cumulative total count of network packets received.
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# TYPE ecs_network_receive_packets_total counter
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ecs_network_receive_packets_total{interface="eth1"} 8084
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# HELP ecs_network_transmit_bytes_total Cumulative total size of network packets transmitted in bytes.
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# TYPE ecs_network_transmit_bytes_total counter
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ecs_network_transmit_bytes_total{interface="eth1"} 178817
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# HELP ecs_network_transmit_dropped_total Cumulative total count of network packets dropped in transmit.
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# TYPE ecs_network_transmit_dropped_total counter
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ecs_network_transmit_dropped_total{interface="eth1"} 0
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# HELP ecs_network_transmit_errors_total Cumulative total count of network errors in transmit.
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# TYPE ecs_network_transmit_errors_total counter
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ecs_network_transmit_errors_total{interface="eth1"} 0
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# HELP ecs_network_transmit_packets_total Cumulative total count of network packets transmitted.
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# TYPE ecs_network_transmit_packets_total counter
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ecs_network_transmit_packets_total{interface="eth1"} 897
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# HELP ecs_task_cpu_limit_vcpus Configured task CPU limit in vCPUs (1 vCPU = 1024 CPU units). This is optional when running on EC2; if no limit is set, this metric has no value.
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# TYPE ecs_task_cpu_limit_vcpus gauge
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ecs_task_cpu_limit_vcpus 0.25
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# HELP ecs_task_ephemeral_storage_allocated_bytes Configured Fargate task ephemeral storage allocated size in bytes.
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# TYPE ecs_task_ephemeral_storage_allocated_bytes gauge
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ecs_task_ephemeral_storage_allocated_bytes 2.1491613696e+10
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# HELP ecs_task_ephemeral_storage_used_bytes Current Fargate task ephemeral storage usage in bytes.
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# TYPE ecs_task_ephemeral_storage_used_bytes gauge
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ecs_task_ephemeral_storage_used_bytes 3.7748736e+07
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# HELP ecs_task_image_pull_start_timestamp_seconds The time at which the task started pulling docker images for its containers.
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# TYPE ecs_task_image_pull_start_timestamp_seconds gauge
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ecs_task_image_pull_start_timestamp_seconds 1.737156015124145e+09
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# HELP ecs_task_image_pull_stop_timestamp_seconds The time at which the task stopped (i.e. completed) pulling docker images for its containers.
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# TYPE ecs_task_image_pull_stop_timestamp_seconds gauge
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ecs_task_image_pull_stop_timestamp_seconds 1.7371560172684324e+09
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# HELP ecs_task_memory_limit_bytes Configured task memory limit in bytes. This is optional when running on EC2; if no limit is set, this metric has no value.
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# TYPE ecs_task_memory_limit_bytes gauge
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ecs_task_memory_limit_bytes 5.36870912e+08
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# HELP ecs_task_metadata_info ECS task metadata, sourced from the task metadata endpoint version 4.
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# TYPE ecs_task_metadata_info gauge
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ecs_task_metadata_info{availability_zone="us-east-1a",cluster="arn:aws:ecs:us-east-1:829490980523:cluster/prom-ecs-exporter-sandbox",desired_status="RUNNING",family="prom-ecs-exporter-sandbox-isker-fix-network-metrics-fargate",known_status="RUNNING",launch_type="FARGATE",revision="1",task_arn="arn:aws:ecs:us-east-1:829490980523:task/prom-ecs-exporter-sandbox/c8387acdc4884a0fa13dae78e68a989f"} 1
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```
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## Example task definition
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```
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{
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"ipcMode": null,
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"executionRoleArn": "arn:aws:iam::ACCOUNT_ID:role/ecsTaskExecutionRole",
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"containerDefinitions": [
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{
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"dnsSearchDomains": null,
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"environmentFiles": null,
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"logConfiguration": {
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"logDriver": "awslogs",
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"secretOptions": null,
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"options": {
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"awslogs-group": "/ecs/ecs-exporter",
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"awslogs-region": "us-west-2",
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"awslogs-stream-prefix": "ecs"
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}
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},
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"entryPoint": null,
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"portMappings": [
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{
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"hostPort": 9779,
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"protocol": "tcp",
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"containerPort": 9779
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}
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],
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"command": null,
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"linuxParameters": null,
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"cpu": 0,
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"environment": [],
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"resourceRequirements": null,
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"ulimits": null,
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"dnsServers": null,
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"mountPoints": [],
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"workingDirectory": null,
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"secrets": null,
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"dockerSecurityOptions": null,
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"memory": null,
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"memoryReservation": null,
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"volumesFrom": [],
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"stopTimeout": null,
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"image": "quay.io/prometheuscommunity/ecs-exporter:v0.1.0",
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"startTimeout": null,
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"firelensConfiguration": null,
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"dependsOn": null,
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"disableNetworking": null,
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"interactive": null,
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"healthCheck": null,
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"essential": true,
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"links": null,
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"hostname": null,
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"extraHosts": null,
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"pseudoTerminal": null,
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"user": null,
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"readonlyRootFilesystem": null,
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"dockerLabels": null,
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"systemControls": null,
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"privileged": null,
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"name": "ecs-exporter"
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}
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],
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"placementConstraints": [],
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"memory": "512",
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"taskRoleArn": "arn:aws:iam::ACCOUNT_ID:role/ecsTaskExecutionRole",
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"compatibilities": [
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"EC2",
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"FARGATE"
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],
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"taskDefinitionArn": "arn:aws:ecs:us-west-2:ACCOUNT_ID:task-definition/ecs-exporter:1",
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"family": "ecs-exporter",
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"requiresAttributes": [
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{
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"targetId": null,
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"targetType": null,
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"value": null,
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"name": "com.amazonaws.ecs.capability.logging-driver.awslogs"
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},
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{
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"targetId": null,
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"targetType": null,
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"value": null,
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"name": "ecs.capability.execution-role-awslogs"
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},
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{
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"targetId": null,
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"targetType": null,
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"value": null,
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"name": "com.amazonaws.ecs.capability.docker-remote-api.1.19"
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},
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{
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"targetId": null,
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"targetType": null,
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"value": null,
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"name": "com.amazonaws.ecs.capability.task-iam-role"
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},
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{
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"targetId": null,
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"targetType": null,
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"value": null,
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"name": "com.amazonaws.ecs.capability.docker-remote-api.1.18"
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},
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{
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"targetId": null,
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"targetType": null,
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"value": null,
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"name": "ecs.capability.task-eni"
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}
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],
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"pidMode": null,
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"requiresCompatibilities": [
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"FARGATE"
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],
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"networkMode": "awsvpc",
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"cpu": "256",
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"revision": 1,
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"status": "ACTIVE",
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"inferenceAccelerators": null,
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"proxyConfiguration": null,
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"volumes": []
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}
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```
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Check out the [metrics snapshots](./ecscollector/testdata/snapshots) which
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contain sample metrics emitted by ecs_exporter in the [Prometheus text
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format](https://prometheus.io/docs/instrumenting/exposition_formats/#text-based-format)
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you should expect to see on /metrics. Note that these snapshots behave as if
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`--web.disable-exporter-metrics` were passed when running ecs_exporter, such
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that standard [client_golang](https://github.com/prometheus/client_golang)
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metrics are not included.

Diff for: ‎ecscollector/collector_test.go

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package ecscollector
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import (
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"bytes"
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_ "embed"
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"flag"
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"fmt"
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"io"
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"log/slog"
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"net/http"
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"net/http/httptest"
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"os"
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"path/filepath"
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"testing"
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"github.com/prometheus-community/ecs_exporter/ecsmetadata"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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// Create a metadata client that will always receive the given fixture API
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// responses.
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func fixtureClient(taskMetadata, taskStats []byte) (*ecsmetadata.Client, *httptest.Server) {
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mux := http.NewServeMux()
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mux.HandleFunc("GET /task", func(w http.ResponseWriter, r *http.Request) {
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w.Header().Add("content-type", "application/json")
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w.Write(taskMetadata)
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})
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mux.HandleFunc("GET /task/stats", func(w http.ResponseWriter, r *http.Request) {
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w.Header().Add("content-type", "application/json")
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w.Write(taskStats)
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})
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server := httptest.NewServer(mux)
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return ecsmetadata.NewClient(server.URL), server
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}
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// Create a metadata client that will always receive HTTP 500 API responses.
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// Renders ecs_exporter metrics from the given metadata client to the prometheus
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// text exposition format.
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func renderMetrics(client *ecsmetadata.Client) ([]byte, error) {
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registry := prometheus.NewRegistry()
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registry.MustRegister(NewCollector(client, slog.Default()))
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// It seems that the only way to really get full /metrics output is with
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// promhttp.
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promServer := httptest.NewServer(promhttp.HandlerFor(registry, promhttp.HandlerOpts{}))
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defer promServer.Close()
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resp, err := http.Get(promServer.URL)
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if err != nil {
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return nil, fmt.Errorf("metrics request failed: %w", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != 200 {
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return nil, fmt.Errorf("non-200 metrics response: %v", resp.StatusCode)
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}
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metrics, err := io.ReadAll(resp.Body)
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if err != nil {
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return nil, fmt.Errorf("failed to read metrics response body: %w", err)
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}
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return metrics, nil
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}
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var updateSnapshots = flag.Bool("update-snapshots", false, "update snapshot files")
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func assertSnapshot(t *testing.T, path string, actual []byte) {
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snapshot, _ := os.ReadFile(path)
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if !bytes.Equal(actual, snapshot) {
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if *updateSnapshots {
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os.MkdirAll(filepath.Dir(path), 0750)
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os.WriteFile(path, actual, 0666)
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t.Logf("updated snapshot: %s", path)
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} else {
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t.Fatalf("snapshot outdated, set the -update-snapshots flag to update: %s", path)
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}
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}
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}
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//go:embed testdata/fixtures/fargate_task_metadata.json
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var fargateTaskMetadata []byte
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//go:embed testdata/fixtures/fargate_task_stats.json
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var fargateTaskStats []byte
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//go:embed testdata/fixtures/ec2_task_metadata.json
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var ec2TaskMetadata []byte
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//go:embed testdata/fixtures/ec2_task_stats.json
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var ec2TaskStats []byte
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func TestFargateMetrics(t *testing.T) {
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metadataClient, metadataServer := fixtureClient(fargateTaskMetadata, fargateTaskStats)
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defer metadataServer.Close()
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metrics, err := renderMetrics(metadataClient)
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if err != nil {
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t.Fatalf("failed to render metrics: %v", err)
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}
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assertSnapshot(t, "testdata/snapshots/fargate_metrics.txt", metrics)
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}
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func TestEc2Metrics(t *testing.T) {
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metadataClient, metadataServer := fixtureClient(ec2TaskMetadata, ec2TaskStats)
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defer metadataServer.Close()
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metrics, err := renderMetrics(metadataClient)
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if err != nil {
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t.Fatalf("failed to render metrics: %v", err)
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}
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assertSnapshot(t, "testdata/snapshots/ec2_metrics.txt", metrics)
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}

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