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Add support for templating to kube's
--set-context-override (#30157)
* Add support for templating to kube's `--set-context-override`
This PR adds templating support for `tsh kube login --set-context-name`.
This allows executing `tsh kube login --all
--set-context-name="{{.KubeName}}` to generate a kube config with every
cluster the user has access to but without the Teleport's cluster name
prefix.
Changelog: Extend `tsh kube login --set-context-name` to support
templating functions.
* rename function
---------
Signed-off-by: Tiago Silva <tiago.silva@goteleport.com>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,103 @@ | ||
| // Copyright 2023 Gravitational, Inc | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| // Package kubeconfig manages teleport entries in a local kubeconfig file. | ||
| package kubeconfig | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "text/template" | ||
|
|
||
| "github.com/gravitational/trace" | ||
| ) | ||
|
|
||
| const ( | ||
| // supportedFunctionsMsg is a message that lists all supported template | ||
| // vars. | ||
| supportedFunctionsMsg = "Supported template functions:\n" + | ||
| " - `{{ .KubeName }}` - the name of the Kubernetes cluster\n" + | ||
| " - `{{ .ClusterName }}` - the name of the Teleport cluster\n" | ||
| ) | ||
|
|
||
| // CheckContextOverrideTemplate tests if the given template is valid and can | ||
| // be used to generate different context names for different clusters. | ||
| func CheckContextOverrideTemplate(temp string) error { | ||
| if temp == "" { | ||
| return nil | ||
| } | ||
| tmpl, err := parseContextOverrideTemplate(temp) | ||
| if err != nil { | ||
| return trace.Wrap(parseContextOverrideError(err)) | ||
| } | ||
| val1, err1 := executeKubeContextTemplate(tmpl, "cluster", "kube1") | ||
| val2, err2 := executeKubeContextTemplate(tmpl, "cluster", "kube2") | ||
| if err1 != nil || err2 != nil { | ||
| return trace.Wrap(parseContextOverrideError(nil)) | ||
| } | ||
|
|
||
| if val1 != val2 { | ||
| return nil | ||
| } | ||
|
|
||
| return trace.BadParameter( | ||
| "using the same context override template for different clusters is not allowed.\n" + | ||
| "Please ensure the template syntax includes {{ .KubeName }} and try again.\n" + | ||
| supportedFunctionsMsg, | ||
| ) | ||
| } | ||
|
|
||
| // parseContextOverrideTemplate parses the given template and returns a | ||
| // template object that can be used to generate different context names for | ||
| // different clusters. | ||
| // Otherwise, it returns an error. | ||
| func parseContextOverrideTemplate(temp string) (*template.Template, error) { | ||
| if temp == "" { | ||
| return nil, nil | ||
| } | ||
| tmpl, err := template.New("context_override").Parse(temp) | ||
| if err != nil { | ||
| return nil, trace.Wrap(parseContextOverrideError(err)) | ||
| } | ||
| return tmpl, nil | ||
| } | ||
|
|
||
| // parseContextOverrideError returns a formatted error message for the given | ||
| // error. | ||
| func parseContextOverrideError(err error) error { | ||
| msg := "failed to parse context override template.\n" + | ||
| "Please check the template syntax and try again.\n" + | ||
| supportedFunctionsMsg | ||
| if err == nil { | ||
| return trace.BadParameter(msg) | ||
| } | ||
| return trace.BadParameter( | ||
| msg+ | ||
| "Error: %v", err, | ||
| ) | ||
| } | ||
|
|
||
| // executeKubeContextTemplate executes the given template and returns the | ||
| // generated context name. | ||
| func executeKubeContextTemplate(tmpl *template.Template, clusterName, kubeName string) (string, error) { | ||
| contextEntry := struct { | ||
| ClusterName string | ||
| KubeName string | ||
| }{ | ||
| ClusterName: clusterName, | ||
| KubeName: kubeName, | ||
| } | ||
| var buf bytes.Buffer | ||
| err := tmpl.Execute(&buf, contextEntry) | ||
| return buf.String(), trace.Wrap(err) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,74 @@ | ||
| // Copyright 2023 Gravitational, Inc | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| // Package kubeconfig manages teleport entries in a local kubeconfig file. | ||
| package kubeconfig | ||
|
|
||
| import ( | ||
| "testing" | ||
|
|
||
| "github.com/stretchr/testify/require" | ||
| ) | ||
|
|
||
| func TestCheckContextOverrideTemplate(t *testing.T) { | ||
| type args struct { | ||
| temp string | ||
| } | ||
| tests := []struct { | ||
| name string | ||
| args args | ||
| assertErr require.ErrorAssertionFunc | ||
| errContains string | ||
| }{ | ||
| { | ||
| name: "empty template", | ||
| args: args{ | ||
| temp: "", | ||
| }, | ||
| assertErr: require.NoError, | ||
| }, | ||
| { | ||
| name: "valid template", | ||
| args: args{ | ||
| temp: "{{ .KubeName }}-{{ .ClusterName }}", | ||
| }, | ||
| assertErr: require.NoError, | ||
| }, | ||
| { | ||
| name: "invalid template", | ||
| args: args{ | ||
| temp: "{{ .KubeName2 }}-{{ .ClusterName }}", | ||
| }, | ||
| assertErr: require.Error, | ||
| errContains: "failed to parse context override template", | ||
| }, | ||
| { | ||
| name: "invalid template", | ||
| args: args{ | ||
| temp: "{{ .ClusterName }}", | ||
| }, | ||
| assertErr: require.Error, | ||
| errContains: "using the same context override template for different clusters is not allowed", | ||
| }, | ||
| } | ||
| for _, tt := range tests { | ||
| t.Run(tt.name, func(t *testing.T) { | ||
| err := CheckContextOverrideTemplate(tt.args.temp) | ||
| tt.assertErr(t, err) | ||
| if err != nil { | ||
| require.ErrorContains(t, err, tt.errContains) | ||
| } | ||
| }) | ||
| } | ||
| } |
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