In some environments, the 'home directory' cannot be accessed

[futugyou]

I encountered an error while deploying my Golang application using hcp-sdk-go on Vercel Functions. When calling NewHCPConfig, the following error occurred:
failed to retrieve user's home directory path: $home.

After checking the source code, I found that NewHCPConfig (source) calls setTokenSource (source), which in turn calls TokenCacheFile (source), leading to the error (source).

[huikang]

@futugyou , if I understand you correctly, making the user's home directory configurable may resolve your issue.

[futugyou]

@futugyou , if I understand you correctly, making the user's home directory configurable may resolve your issue.

Making the user's home directory configurable might help in cases where the application doesn't have permission to access os.UserHomeDir(), but it doesn't really apply to my situation.
I'm running in a Vercel serverless environment, where this logic—specifically the call to files.TokenCacheFile()—shouldn't be executed at all, given the nature of serverless platforms.

As noted in the comment above files.TokenCacheFile() (// TODO: make this configurable ), it seems I should have had the option to bypass this logic entirely.

I'm quite surprised this issue has persisted for so long.

[huikang]

Thanks for clarifying, so I guess what we can do is

     opt := config.WithTokenFile(`path-to-token-file`),
     
     // Construct HCP config
     hcpConfig, _ := config.NewHCPConfig(opts...)

The configured token file will be passed down to TokenCacheFile

[futugyou]

I understand that the current implementation defaults to caching the token in a local file. However, in certain environments such as serverless platforms, each request may be handled by a different instance, making local file caching ineffective or irrelevant. Therefore, I believe it would be beneficial to introduce a configuration option that allows users to explicitly enable or disable token caching.
In my current use case, disabling token caching is the more appropriate choice.

[huikang]

#293 should resolve this issue: you can configure the location of the cached token.

SInce the container/serverless environment is ephemeral, hcp-sdk-go will force login. An alternative is to force login

    err := hcpConfig.Logout() // Discard the currently cached credentials (if any)
    _, err = hcpConfig.Token() // Fetching a token will trigger a login 

https://github.com/hashicorp/hcp-sdk-go?tab=readme-ov-file#user-session