Allow specification of client_id by env var

[aidy]

Specifying client_id by env var allows us to pre-populate a namespace with all the relevant authentication details.

Currently, we have to populate a secret with a private key, and then create a deployment given the client id. Specifying via an env var would allow us to create/rotate deployments and credentials independently of each other.

e.g.

env:
 - name: CLIENT_ID
   valueFrom:
     configMapKeyRef:
       name: venafi-agent-svc-account
       key: client_id

[wallrj]

@aidy I don't think it's well documented, but you can set the defaults for all the command line flags using PREFLIGHT_ environment variables. E.g.

PREFLIGHT_INSTALL_NAMESPACE=venafi \
PREFLIGHT_CLIENT_ID=foo \
PREFLIGHT_PRIVATE_KEY_PATH=/dev/null \
./preflight agent

I1108 09:13:21.387671  341204 run.go:57] "Starting" logger="Run" version="development" commit=""
I1108 09:13:21.389308  341204 config.go:395] "Using the Venafi Cloud Key Pair Service Account auth mode since --client-id and --private-key-path were specified." logger="Run"
I1108 09:13:21.389392  341204 config.go:479] "ignoring the venafi-cloud.uploader_id field in the config file. This field is not needed in Venafi Cloud Key Pair Service Account mode." logger="Run"
I1108 09:13:21.389408  341204 config.go:531] "Using period from config" logger="Run" period="1m0s"
I1108 09:13:21.389454  341204 config.go:737] "Loading upload_path from \"venafi-cloud\" configuration." logger="Run"
E1108 09:13:21.389576  341204 root.go:53] "Exiting due to error" err=<
        While evaluating configuration: validating creds: failed loading config using the Venafi Cloud Key Pair Service Account mode: 1 error occurred:
                * while parsing private key file: while decoding the PEM-encoded private key /dev/null, its content were:

 > exit-code=1

Does that solve your problem?

See

jetstack-secure/cmd/root.go

Lines 37 to 54 in 1f00f09

	func setFlagsFromEnv(prefix string, fs *pflag.FlagSet) {
	set := map[string]bool{}
	fs.Visit(func(f *pflag.Flag) {
	set[f.Name] = true
	})
	fs.VisitAll(func(f *pflag.Flag) {
	// ignore flags set from the commandline
	if set[f.Name] {
	return
	}
	// remove trailing _ to reduce common errors with the prefix, i.e. people setting it to MY_PROG_
	cleanPrefix := strings.TrimSuffix(prefix, "_")
	name := fmt.Sprintf("%s_%s", cleanPrefix, strings.Replace(strings.ToUpper(f.Name), "-", "_", -1))
	if e, ok := os.LookupEnv(name); ok {
	_ = f.Value.Set(e)
	}
	})
	}

[maelvls]

I wasn't aware of these env variable either. Thanks for pointing them out, Richard. @aidy Does PREFLIGHT_CLIENT_ID satisfy your needs?

(We should somehow have these env vars documented somewhere, though)

[maelvls]

Hey, I'll close this PR for now.

@aidy let me know if you want to re-open it 👍