Google Cloud Credential provider which allows sourcing credentials from an external process.
Essentially, its a credential source which allows the delegation of acquiring GCP access_tokens
to arbitrary binaries you have access to at runtime.
The arbitrary binary would use whatever means it has available (kerberos, ldap, saml-cli, etc) to get a GCP access_token
.
From there, the token is given surfaced as a refreshable credential source you can directly use with a GCP library.
This is similar to several systems that provide such delegation.
- Kubernetes kubectl credential plugin
- AWS Process Credentials
Needless to say, use this after very careful consideration: this library will attempt to execute a binary on the system where its run (ofcource the process running using the library would need access to run the script anyway)
NOTE these samples are NOT supported by google; its just something done on a weekend...
As its a weekend project, caveat emptor. The code is alpha quality and I didn't have time to push it to maven central, npm, etc.
If you want it there, please review the code, provide suggestions and improvements here
golang
: https://github.com/salrashid123/gcp_process_credentials_gopython
: https://github.com/salrashid123/gcp_process_credentials_pyjava
: https://github.com/salrashid123/gcp_process_credentials_javanode
: https://github.com/salrashid123/gcp_process_credentials_node
See the "examples" folder in each
Each library above will invoke a binary, pass it some args and env var.
The response back from the binary must
be valid JSON in the form
{
"access_token": "ya29....",
"expires_in": 3600,
"token_type": "Bearer"
}
access_token
: your access tokenexpires_in
: how many seconds this token is valid fortoken_type
: usually just a bearer token
For a quick example in python, the following will read a token file and use that for credentials:
(see examples/
folder)
let targetClient = new GCPProcessCredentials({
cmd: "/usr/bin/cat",
args: ["/tmp/token.txt"],
env : {'foo': 'bar'},
parser: null
});
let targetClient = new GCPProcessCredentials({
cmd: "gcloud",
args: ["auth", "print-access-token"],
parser: null
});
const {Storage} = require('@google-cloud/storage');
const storage = new Storage({
projectId: 'core-eso',
authClient: targetClient,
});
ofcourse the file here /tmp/token.txt
must be the json file format described above
If your binary does not provide the exact json format, your can define a parser interface to 'translate' the credential for you.
For example, gcloud auth print-access-token
returns just the access token with an annoying newline character from stdout.
You an provide an interface to do the translation like this:
class gcloudParser {
constructor() {}
parse(i) {
return '{ "access_token": "' + i.toString().replace(/\n$/, '') +'", "expires_in": 3600, "token_type": "Bearer" }'
}
}
let targetClient = new GCPProcessCredentials({
cmd: "gcloud",
args: ["auth", "print-access-token"],
parser: new gcloudParser()
});
const {Storage} = require('@google-cloud/storage');
const storage = new Storage({
projectId: 'core-eso',
authClient: targetClient,
});
You might be asking...why cant' i just run the binary on my own in code, get the token an inject it as a credential like this??
Well, the, token is not refreshable and your client library will need to manage that. On the other hand, if you use this library, it will automatically refresh the token by calling the binary when its nearing expiration
Other References AWS->GCP Process Credential Plugin