A grammar for the Grafana Alloy configuration language, supports all types and most common uses of the language.
Below is an example config taken from the Alloy docs:
// Collection: mount a local directory with a certain path spec
local.file_match "applogs" {
path_targets = [{"__path__" = "/tmp/app-logs/app.log"}]
}
// Collection: Take the file match as input, and scrape those mounted log files
loki.source.file "local_files" {
targets = local.file_match.applogs.targets
// This specifies which component should process the logs next, the "link in the chain"
forward_to = [loki.process.add_new_label.receiver]
}
// Transformation: pull some data out of the log message, and turn it into a label
loki.process "add_new_label" {
stage.logfmt {
mapping = {
"extracted_level" = "level",
}
}
// Add the value of "extracted_level" from the extracted map as a "level" label
stage.labels {
values = {
"level" = "extracted_level",
}
}
// The next link in the chain is the local_loki "receiver" (receives the telemetry)
forward_to = [loki.write.local_loki.receiver]
}
// Anything that comes into this component gets written to the loki remote API
loki.write "local_loki" {
endpoint {
url = "http://loki:3100/loki/api/v1/push"
}
}
Will be parsed into this AST:
(source_file [1, 0] - [39, 0]
(comment [1, 0] - [1, 63])
(block [2, 0] - [4, 1]
name: (identifier [2, 0] - [2, 16])
label: (string [2, 17] - [2, 26])
(attribute [3, 4] - [3, 59]
name: (identifier [3, 4] - [3, 16])
value: (expression [3, 19] - [3, 59]
(array [3, 19] - [3, 59]
(expression [3, 20] - [3, 58]
(object [3, 20] - [3, 58]
(attribute [3, 21] - [3, 57]
name: (string [3, 21] - [3, 31])
value: (expression [3, 34] - [3, 57]
(string [3, 34] - [3, 57])))))))))
(comment [6, 0] - [6, 79])
(block [7, 0] - [12, 1]
name: (identifier [7, 0] - [7, 16])
label: (string [7, 17] - [7, 30])
(attribute [8, 4] - [8, 49]
name: (identifier [8, 4] - [8, 11])
value: (expression [8, 17] - [8, 49]
(identifier [8, 17] - [8, 49])))
(comment [10, 4] - [10, 91])
(attribute [11, 4] - [11, 54]
name: (identifier [11, 4] - [11, 14])
value: (expression [11, 17] - [11, 54]
(array [11, 17] - [11, 54]
(expression [11, 18] - [11, 53]
(identifier [11, 18] - [11, 53]))))))
(comment [14, 0] - [14, 82])
(block [15, 0] - [31, 1]
name: (identifier [15, 0] - [15, 12])
label: (string [15, 13] - [15, 28])
(block [16, 4] - [20, 5]
name: (identifier [16, 4] - [16, 16])
(attribute [17, 8] - [19, 9]
name: (identifier [17, 8] - [17, 15])
value: (expression [17, 18] - [19, 9]
(object [17, 18] - [19, 9]
(attribute [18, 12] - [18, 39]
name: (string [18, 12] - [18, 29])
value: (expression [18, 32] - [18, 39]
(string [18, 32] - [18, 39])))))))
(comment [22, 4] - [22, 83])
(block [23, 4] - [27, 5]
name: (identifier [23, 4] - [23, 16])
(attribute [24, 8] - [26, 9]
name: (identifier [24, 8] - [24, 14])
value: (expression [24, 17] - [26, 9]
(object [24, 17] - [26, 9]
(attribute [25, 12] - [25, 39]
name: (string [25, 12] - [25, 19])
value: (expression [25, 22] - [25, 39]
(string [25, 22] - [25, 39])))))))
(comment [29, 4] - [29, 87])
(attribute [30, 4] - [30, 49]
name: (identifier [30, 4] - [30, 14])
value: (expression [30, 17] - [30, 49]
(array [30, 17] - [30, 49]
(expression [30, 18] - [30, 48]
(identifier [30, 18] - [30, 48]))))))
(comment [33, 0] - [33, 78])
(block [34, 0] - [38, 1]
name: (identifier [34, 0] - [34, 10])
label: (string [34, 11] - [34, 23])
(block [35, 4] - [37, 5]
name: (identifier [35, 4] - [35, 12])
(attribute [36, 8] - [36, 49]
name: (identifier [36, 8] - [36, 11])
value: (expression [36, 14] - [36, 49]
(string [36, 14] - [36, 49]))))))