From 2b1138c118e587dc0c3ddeab792036e311f42c0f Mon Sep 17 00:00:00 2001
From: Sebastiaan van Stijn <github@gone.nl>
Date: Tue, 29 Sep 2020 17:01:55 +0200
Subject: [PATCH] Fix initializing client modifying custom HTTPHeaders

When initializing the API client, the User-Agent was added to any custom
HTTPHeaders that were configured. However, because the map was not properly
dereferenced, the original map was modified, causing the User-Agent to also
be saved to config.json after `docker login` and `docker logout`:

Before this change;

    $ cat ~/.docker/config.json
    cat: can't open '/root/.docker/config.json': No such file or directory

    $ docker login -u myusername
    Password:
    ...
    Login Succeeded

    $ cat ~/.docker/config.json
    {
        "auths": {
            "https://index.docker.io/v1/": {
                "auth": "<base64 auth>"
            }
        },
        "HttpHeaders": {
            "User-Agent": "Docker-Client/19.03.12 (linux)"
        }
    }

    $ docker logout
    {
        "auths": {},
        "HttpHeaders": {
            "User-Agent": "Docker-Client/19.03.12 (linux)"
        }
    }

After this change:

    $ cat ~/.docker/config.json
    cat: can't open '/root/.docker/config.json': No such file or directory

    $ docker login -u myusername
    Password:
    ...
    Login Succeeded

    $ cat ~/.docker/config.json
    {
        "auths": {
            "https://index.docker.io/v1/": {
                "auth": "<base64 auth>"
            }
        }
    }

    $ docker logout
    Removing login credentials for https://index.docker.io/v1/

    $ cat ~/.docker/config.json
    {
        "auths": {}
    }

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
---
 cli/command/cli.go      | 6 +++---
 cli/command/cli_test.go | 1 +
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/cli/command/cli.go b/cli/command/cli.go
index a9e7e30763..7b5048e98f 100644
--- a/cli/command/cli.go
+++ b/cli/command/cli.go
@@ -308,9 +308,9 @@ func newAPIClientFromEndpoint(ep docker.Endpoint, configFile *configfile.ConfigF
 	if err != nil {
 		return nil, err
 	}
-	customHeaders := configFile.HTTPHeaders
-	if customHeaders == nil {
-		customHeaders = map[string]string{}
+	customHeaders := make(map[string]string, len(configFile.HTTPHeaders))
+	for k, v := range configFile.HTTPHeaders {
+		customHeaders[k] = v
 	}
 	customHeaders["User-Agent"] = UserAgent()
 	clientOpts = append(clientOpts, client.WithHTTPHeaders(customHeaders))
diff --git a/cli/command/cli_test.go b/cli/command/cli_test.go
index 32c999df75..83f42e9df0 100644
--- a/cli/command/cli_test.go
+++ b/cli/command/cli_test.go
@@ -45,6 +45,7 @@ func TestNewAPIClientFromFlags(t *testing.T) {
 	}
 	assert.Check(t, is.DeepEqual(expectedHeaders, apiclient.(*client.Client).CustomHTTPHeaders()))
 	assert.Check(t, is.Equal(api.DefaultVersion, apiclient.ClientVersion()))
+	assert.DeepEqual(t, configFile.HTTPHeaders, map[string]string{"My-Header": "Custom-Value"})
 }
 
 func TestNewAPIClientFromFlagsForDefaultSchema(t *testing.T) {