feat: [CDE-116]: Adding SCM pkg responsible for fetching devcontainer config from public code repos (#2141)

app/gitspace/scm/scm.go

@@ -0,0 +1,141 @@
+// Copyright 2023 Harness, 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 scm
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"regexp"
+	"strings"
+
+	"github.com/harness/gitness/git/command"
+	"github.com/harness/gitness/types"
+
+	"github.com/google/uuid"
+	"github.com/rs/zerolog/log"
+)
+
+var _ SCM = (*scm)(nil)
+
+type SCM interface {
+	// DevcontainerConfig fetches devcontainer config file from the given repo and branch.
+	DevcontainerConfig(ctx context.Context, gitspaceConfig *types.GitspaceConfig) (*types.DevcontainerConfig, error)
+}
+
+type scm struct{}
+
+func NewSCM() SCM {
+	return &scm{}
+}
+
+func (s scm) DevcontainerConfig(
+	ctx context.Context,
+	gitspaceConfig *types.GitspaceConfig,
+) (*types.DevcontainerConfig, error) {
+	gitWorkingDirectory := "/tmp/git/"
+	cloneDir := gitWorkingDirectory + uuid.New().String()
+	err := os.MkdirAll(cloneDir, os.ModePerm)
+	if err != nil {
+		return nil, fmt.Errorf("error creating directory %s: %w", cloneDir, err)
+	}
+	defer func() {
+		err = os.RemoveAll(cloneDir)
+		if err != nil {
+			log.Ctx(ctx).Warn().Err(err).Msg("Unable to remove working directory")
+		}
+	}()
+	filePath := ".devcontainer/devcontainer.json"
+	err = validateArgs(gitspaceConfig)
+	if err != nil {
+		return nil, fmt.Errorf("invalid branch or url: %w", err)
+	}
+
+	log.Info().Msg("Cloning the repository...")
+	cmd := command.New("clone",
+		command.WithFlag("--branch", gitspaceConfig.Branch),
+		command.WithFlag("--no-checkout"),
+		command.WithFlag("--depth", "1"),
+		command.WithArg(gitspaceConfig.CodeRepoURL),
+		command.WithArg(cloneDir),
+	)
+	err = cmd.Run(
+		ctx,
+		command.WithDir(cloneDir),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to clone repository %s: %w", gitspaceConfig.CodeRepoURL, err)
+	}
+
+	var lsTreeOutput bytes.Buffer
+	lsTreeCmd := command.New("ls-tree",
+		command.WithArg("HEAD"),
+		command.WithArg(filePath),
+	)
+	err = lsTreeCmd.Run(
+		ctx,
+		command.WithDir(cloneDir),
+		command.WithStdout(&lsTreeOutput),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list files in repository %s: %w", cloneDir, err)
+	}
+
+	if lsTreeOutput.Len() == 0 {
+		log.Info().Msg("File not found, returning empty devcontainerConfig")
+		emptyConfig := &types.DevcontainerConfig{}
+		return emptyConfig, nil
+	}
+
+	fields := strings.Fields(lsTreeOutput.String())
+	blobSHA := fields[2]
+
+	var catFileOutput bytes.Buffer
+	catFileCmd := command.New("cat-file", command.WithFlag("-p"), command.WithArg(blobSHA))
+	err = catFileCmd.Run(
+		ctx,
+		command.WithDir(cloneDir),
+		command.WithStderr(io.Discard),
+		command.WithStdout(&catFileOutput),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to checkout devcontainer file from path %s: %w", filePath, err)
+	}
+
+	sanitizedJSON := removeComments(catFileOutput.Bytes())
+
+	var config types.DevcontainerConfig
+	err = json.Unmarshal(sanitizedJSON, &config)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse devcontainer json: %w", err)
+	}
+
+	return &config, nil
+}
+
+func removeComments(input []byte) []byte {
+	blockCommentRegex := regexp.MustCompile(`(?s)/\*.*?\*/`)
+	input = blockCommentRegex.ReplaceAll(input, nil)
+	lineCommentRegex := regexp.MustCompile(`//.*`)
+	return lineCommentRegex.ReplaceAll(input, nil)
+}
+
+func validateArgs(_ *types.GitspaceConfig) error {
+	// TODO Validate the args
+	return nil
+}

app/gitspace/scm/wire.go

@@ -0,0 +1,26 @@
+// Copyright 2023 Harness, 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 scm
+
+import "github.com/google/wire"
+
+// WireSet provides a wire set for this package.
+var WireSet = wire.NewSet(
+	ProvideSCM,
+)
+
+func ProvideSCM() SCM {
+	return NewSCM()
+}

types/devcontainer_config.go

@@ -0,0 +1,21 @@
+// Copyright 2023 Harness, 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 types
+
+// DevcontainerConfig is parsed from code repos and follows the devcontainer.json spec. It uses camelCase.
+type DevcontainerConfig struct {
+	Image             string `json:"image"`
+	PostCreateCommand string `json:"postCreateCommand"` //nolint:tagliatelle
+}

types/gitspace_config.go

@@ -0,0 +1,21 @@
+// Copyright 2023 Harness, 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 types
+
+// TODO: These are placeholders to enable SCM dev. These are to be replaced with complete structs in upcoming PRs.
+type GitspaceConfig struct {
+	CodeRepoURL string
+	Branch      string
+}