forked from jamietsao/aws-ssm-env
/
main.go
250 lines (208 loc) · 5.43 KB
/
main.go
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package main
import (
"context"
"flag"
"fmt"
"log"
"os"
"strconv"
"strings"
"time"
"github.com/aws/aws-sdk-go-v2/aws/retry"
"github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/service/ssm"
"github.com/aws/aws-sdk-go-v2/service/ssm/types"
)
const (
envBackoff = "AWS_SSM_ENV_BACKOFF"
envAttempts = "AWS_SSM_ENV_ATTEMPTS"
)
var (
client *ssm.Client
paths []string
tags []string
)
func main() {
// initialize AWS client
err := initClient()
if err != nil {
log.Fatalf("error initializing client: %v", err)
os.Exit(1)
}
// initialize command line flags
initFlags()
// fetch parameters
params, err := fetchParams(paths)
if err != nil {
log.Fatalf("error fetching parameters: %v", err)
os.Exit(2)
}
// print as env variables
printParams(params)
}
func initClient() error {
// Create base config
cfg, err := config.LoadDefaultConfig(context.TODO())
if err != nil {
return err
}
// Create retryer with custom backoff if env var present
customRetryer := retry.NewStandard(func(o *retry.StandardOptions) {
backoffStr := os.Getenv(envBackoff)
if backoffStr != "" {
backoff, err := time.ParseDuration(backoffStr)
if err == nil {
o.MaxBackoff = backoff
}
}
attemptsStr := os.Getenv(envAttempts)
if attemptsStr != "" {
attempts, err := strconv.Atoi(attemptsStr)
if err == nil {
o.MaxAttempts = attempts
}
}
})
// Create SSM client with retryer
client = ssm.NewFromConfig(cfg, func(o *ssm.Options) {
o.Retryer = customRetryer
})
return nil
}
func initFlags() {
pathsFlag := flag.String("paths", "", "comma delimited string of parameter path hierarchies")
tagsFlag := flag.String("tags", "", "comma delimited string of tags to filter by")
flag.Parse()
initPaths(pathsFlag)
initTags(tagsFlag)
}
func initPaths(pathsFlag *string) {
if *pathsFlag != "" {
paths = strings.Split(*pathsFlag, ",")
}
// ensure only path hierarchies were given
for _, path := range paths {
if !strings.Contains(path, "/") {
fmt.Printf("Invalid path: '%s' - only path hierarchies are supported (e.g. '/production/webapp/')\n", path)
os.Exit(1)
}
}
}
func initTags(tagsFlag *string) {
if *tagsFlag != "" {
tags = strings.Split(*tagsFlag, ",")
}
}
func fetchParams(paths []string) ([]types.Parameter, error) {
// create tag filters
tagFilters := make([]types.ParameterStringFilter, len(tags))
for i, tag := range tags {
tagFilter := fmt.Sprintf("tag:%s", tag)
tagFilters[i] = types.ParameterStringFilter{
Key: &tagFilter,
}
}
// TEMP: until parameter-filters work for get-parameters-by-path
// - https://docs.aws.amazon.com/cli/latest/reference/ssm/get-parameters-by-path.html ("This API action doesn't support filtering by tags.")
// - https://github.com/aws/aws-cli/issues/2850)
//
// 1) retrieve parameters by path via get-parameters-by-path
// 2) retrieve parameters by tags via describe-parameters
// 3) calculate intersection of two sets
// retrieve params for given paths
params, err := getParamsByPath(paths)
if err != nil {
return nil, err
}
// retrieve all parameters with given tags
// but don't bother if no tags were given
if len(tags) > 0 {
paramNames, err := describeParams(tagFilters)
if err != nil {
return nil, err
}
// return intersection of two sets
return calcIntersection(paramNames, params), nil
}
// just return all parameters by path if no tags given
return params, nil
}
func describeParams(filters []types.ParameterStringFilter) ([]string, error) {
paramNames := make([]string, 0)
done := false
var nextToken string
for !done {
input := &ssm.DescribeParametersInput{
ParameterFilters: filters,
}
if nextToken != "" {
input.NextToken = &nextToken
}
output, err := client.DescribeParameters(context.TODO(), input)
if err != nil {
return paramNames, err
}
for _, param := range output.Parameters {
paramNames = append(paramNames, *param.Name)
}
// there are more parameters if nextToken is given in response
if output.NextToken != nil {
nextToken = *output.NextToken
} else {
done = true
}
}
return paramNames, nil
}
func getParamsByPath(paths []string) ([]types.Parameter, error) {
params := make([]types.Parameter, 0)
// retrieve params for all paths
for _, path := range paths {
done := false
var nextToken string
for !done {
input := &ssm.GetParametersByPathInput{
Path: &path,
Recursive: true,
WithDecryption: true,
}
if nextToken != "" {
input.NextToken = &nextToken
}
output, err := client.GetParametersByPath(context.TODO(), input)
if err != nil {
return params, err
}
params = append(params, output.Parameters...)
// there are more parameters for this path if nextToken is given in response
if output.NextToken != nil {
nextToken = *output.NextToken
} else {
done = true
}
}
}
return params, nil
}
func calcIntersection(paramNames []string, params []types.Parameter) []types.Parameter {
// build map lookup
lookup := make(map[string]bool)
for _, paramName := range paramNames {
lookup[paramName] = true
}
// calculate intersection
union := make([]types.Parameter, 0)
for _, param := range params {
if lookup[*param.Name] {
union = append(union, param)
}
}
return union
}
func printParams(params []types.Parameter) {
for _, param := range params {
split := strings.Split(*param.Name, "/")
name := split[len(split)-1]
fmt.Printf("%s=%s\n", strings.ToUpper(name), *param.Value)
}
}