docs: added environment variables documentation

[HariSekhon]

I'd like an environment variables documentation reference page.

It's the sort of thing I use a lot in other projects documentation so I've created one.

I've added a documentation page on some useful environment variables that I add a lot as I've pieced these together over time from other pages, this is slightly different to the build environment page, but feel free to incorporate or restructure this as you see fit.

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[codecov]

Codecov Report

Merging #8680 (66b0129) into master (b8f6b1c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #8680   +/-   ##
=======================================
  Coverage   45.90%   45.90%           
=======================================
  Files         222      222           
  Lines       26461    26461           
=======================================
  Hits        12146    12146           
  Misses      12658    12658           
  Partials     1657     1657           

Impacted Files	Coverage Δ
util/settings/settings.go	48.16% <0.00%> (ø)

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[crenshaw-dev]

Thanks for the contribution, and apologies for the slow review! Added one nitpick.

[lucasff]

this is ready, no? is there any way to passing the username or password via env?

[HariSekhon]

@lucasff you got me curious, so I've just grep'd the entire ArgoCD codebase for tokens using a new script I just rustled up:

https://github.com/HariSekhon/DevOps-Bash-tools/blob/master/git_grep_env_vars.sh

This has led to me finding some new environment variables:

• ARGOCD_CONFIG_DIR
• XDG_CONFIG_HOME

and some other interesting bits:

pkg/apiclient/apiclient.go: EnvArgoCDAuthToken = "ARGOCD_AUTH_TOKEN"
pkg/apiclient/apiclient.go: EnvArgoCDServer = "ARGOCD_SERVER"
pkg/apiclient/apiclient.go: EnvArgoCDgRPCMaxSizeMB = "ARGOCD_GRPC_MAX_SIZE_MB"
...

common/common.go:   EnvAppConfigPath = "ARGOCD_APP_CONF_PATH"
common/common.go:   EnvControllerReplicas = "ARGOCD_CONTROLLER_REPLICAS"
common/common.go:   EnvControllerShard = "ARGOCD_CONTROLLER_SHARD"
common/common.go:   EnvEnableGRPCTimeHistogramEnv = "ARGOCD_ENABLE_GRPC_TIME_HISTOGRAM"
common/common.go:   EnvGitAttemptsCount = "ARGOCD_GIT_ATTEMPTS_COUNT"
common/common.go:   EnvGitRetryDuration = "ARGOCD_GIT_RETRY_DURATION"
common/common.go:   EnvGitRetryFactor = "ARGOCD_GIT_RETRY_FACTOR"
common/common.go:   EnvGitRetryMaxDuration = "ARGOCD_GIT_RETRY_MAX_DURATION"
common/common.go:   EnvGitSubmoduleEnabled = "ARGOCD_GIT_MODULES_ENABLED"
common/common.go:   EnvGithubAppCredsExpirationDuration = "ARGOCD_GITHUB_APP_CREDS_EXPIRATION_DURATION"
common/common.go:   EnvGnuPGHome = "ARGOCD_GNUPGHOME"
common/common.go:   EnvHelmIndexCacheDuration = "ARGOCD_HELM_INDEX_CACHE_DURATION"
common/common.go:   EnvLogFormat = "ARGOCD_LOG_FORMAT"
common/common.go:   EnvLogLevel = "ARGOCD_LOG_LEVEL"
common/common.go:   EnvMaxCookieNumber = "ARGOCD_MAX_COOKIE_NUMBER"
common/common.go:   EnvPauseGenerationAfterFailedAttempts = "ARGOCD_PAUSE_GEN_AFTER_FAILED_ATTEMPTS"
common/common.go:   EnvPauseGenerationMinutes = "ARGOCD_PAUSE_GEN_MINUTES"
common/common.go:   EnvPauseGenerationRequests = "ARGOCD_PAUSE_GEN_REQUESTS"
common/common.go:   EnvPluginSockFilePath = "ARGOCD_PLUGINSOCKFILEPATH"
common/common.go:   EnvVarRBACDebug = "ARGOCD_RBAC_DEBUG"
common/common.go:   EnvVarSSHDataPath = "ARGOCD_SSH_DATA_PATH"
common/common.go:   EnvVarSSODebug = "ARGOCD_SSO_DEBUG"
common/common.go:   EnvVarTLSDataPath = "ARGOCD_TLS_DATA_PATH"
common/common.go:   EnvWatchAPIBufferSize = "ARGOCD_WATCH_API_BUFFER_SIZE"
...

util/cache/cache.go:    envRedisPassword = "REDIS_PASSWORD"
...

reposerver/cache/cache.go:  cmd.Flags().DurationVar(&repoCacheExpiration, "repo-cache-expiration", env.ParseDurationFromEnv("ARGOCD_REPO_CACHE_EXPIRATION", 24*time.Hour, 0, math.MaxInt64), "Cache expiration for repo state, incl. app lists, app details, manifest generation, revision meta-data")
reposerver/cache/cache.go:  cmd.Flags().DurationVar(&revisionCacheExpiration, "revision-cache-expiration", env.ParseDurationFromEnv("ARGOCD_RECONCILIATION_TIMEOUT", 3*time.Minute, 0, math.MaxInt64), "Cache expiration for cached revision")
...

cmd/argocd-repo-server/commands/argocd_repo_server.go:  command.Flags().BoolVar(&disableTLS, "disable-tls", env.ParseBoolFromEnv("ARGOCD_REPO_SERVER_DISABLE_TLS", false), "Disable TLS on the gRPC endpoint")
cmd/argocd-repo-server/commands/argocd_repo_server.go:  command.Flags().Int64Var(&parallelismLimit, "parallelismlimit", int64(env.ParseNumFromEnv("ARGOCD_REPO_SERVER_PARALLELISM_LIMIT", 0, 0, math.MaxInt32)), "Limit on number of concurrent manifests generate requests. Any value less the 1 means no limit.")
cmd/argocd-repo-server/commands/argocd_repo_server.go:  command.Flags().StringVar(&cmdutil.LogFormat, "logformat", env.StringFromEnv("ARGOCD_REPO_SERVER_LOGFORMAT", "text"), "Set the logging format. One of: text|json")
cmd/argocd-repo-server/commands/argocd_repo_server.go:  command.Flags().StringVar(&cmdutil.LogLevel, "loglevel", env.StringFromEnv("ARGOCD_REPO_SERVER_LOGLEVEL", "info"), "Set the logging level. One of: debug|info|warn|error")

among other environment variables too many to list here.

This is also:

test/e2e/fixture/fixture.go:    EnvAdminPassword = "ARGOCD_E2E_ADMIN_PASSWORD"

but that looks like something only for tests and not what you want, so @lucasff think you'll have to stick with ARGOCD_AUTH_TOKEN.

Since I don't have a thorough experience with all the environment variables, I'd rather limit this PR to the ones I know and merge this so users can actually find it in the current documentation.

[crenshaw-dev]

@HariSekhon yeah documenting the env vars is tricky, because where they get used depends a lot on context. Many of these are specific to running the CLI to start an api server or controller or repo server.

This is a good start, 'cause it's focused on env vars that generically make sense for all CLI operations.

[crenshaw-dev]

Cherry-picked onto 2.4 (I'm trying to be more aggressive about cherry-picking docs-only PRs - they're useful and virtually zero risk.)

[lucasff]

@HariSekhon thanks a lot for doing that! I ended up using manually assigned env vars to run argocd login on my GitHub Actions workflows ;)

[HariSekhon]

@lucasff you're welcome. Btw if it's public, please post a link as I'm always interested in seeing how other people solve CI/CD as I do a lot of this work myself too, and have a couple repos you might find interesting for Jenkins and GitHub-Actions as well.