1. docker
  2. Commit 126d4cf672a274c7af8c72e02f7aa37d64d80417
Browse code

client: remove version-gate for JSON response errors

JSON errors were introduced in API 1.24, and daemons running older versions of
the API would return errors as plain-text. However, such API versions would
also send the corresponding content-type header (text/plain), so we don't
really need to make the code version-dependent; there's already fallbacks
in place to handle JSON-responses that don't use the expected format, in
which case we produce a generic status-code error.

Before this patch, the client would print JSON-responses as-is when the
daemon returned an "API version too old" error;

DOCKER_API_VERSION=v1.10 docker info --format '{{.ID}}'
Error response from daemon: {"message":"client version 1.10 is too old. Minimum supported API version is 1.24, please upgrade your client to a newer version"}

With this patch, the client detects that the response is JSON, and prints
a friendlier error-message to help the user discover their client is too
old;

DOCKER_API_VERSION=v1.10 docker info --format '{{.ID}}'
Error response from daemon: client version 1.10 is too old. Minimum supported API version is 1.24, please upgrade your client to a newer version

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Sebastiaan van Stijn authored on 2025/03/20 20:42:20
Showing 2 changed files
client/request.go
History View file @ 126d4cf
... ... 
@@ -237,7 +237,7 @@ func (cli *Client) checkResponseErr(serverResp *http.Response) (retErr error) {
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 	}
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 	var daemonErr error
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-	if serverResp.Header.Get("Content-Type") == "application/json" && (cli.version == "" || versions.GreaterThan(cli.version, "1.23")) {
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+	if serverResp.Header.Get("Content-Type") == "application/json" {
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 		var errorResponse types.ErrorResponse
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 		if err := json.Unmarshal(body, &errorResponse); err != nil {
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 			return errors.Wrap(err, "Error reading JSON")
client/request_test.go
History View file @ 126d4cf
... ... 
@@ -132,12 +132,15 @@ func TestResponseErrors(t *testing.T) {
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 			expected:    `Error response from daemon: Some error occurred`,
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 		},
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 		{
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-			// API versions before 1.24 did not support JSON errors, and return response as-is.
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+			// API versions before 1.24 did not support JSON errors. Technically,
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+			// we no longer downgrade to older API versions, but we make an
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+			// exception for errors so that older clients would print a more
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+			// readable error.
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 			doc:         "JSON error on old API",
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 			apiVersion:  "1.23",
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-			contentType: "application/json",
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-			response:    `{"message":"Some error occurred"}`,
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-			expected:    `Error response from daemon: {"message":"Some error occurred"}`,
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+			contentType: "text/plain; charset=utf-8",
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+			response:    `client version 1.10 is too old. Minimum supported API version is 1.24, please upgrade your client to a newer version`,
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+			expected:    `Error response from daemon: client version 1.10 is too old. Minimum supported API version is 1.24, please upgrade your client to a newer version`,
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 		},
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 		{
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 			doc:         "plain-text error",