DEVOPS-2496 add max history setting (#12)

* add history_max setting

* update docs

* use suite for env test

internal/run/upgrade.go

@@ -2,6 +2,7 @@ package run
 
 import (
 	"fmt"
+
 	"github.com/pelotech/drone-helm3/internal/env"
 )
 
@@ -22,6 +23,7 @@ type Upgrade struct {
 	force           bool
 	atomic          bool
 	cleanupOnFail   bool
+	historyMax      int
 	certs           *repoCerts
 	createNamespace bool
 	skipCrds        bool
@@ -46,6 +48,7 @@ func NewUpgrade(cfg env.Config) *Upgrade {
 		force:           cfg.Force,
 		atomic:          cfg.AtomicUpgrade,
 		cleanupOnFail:   cfg.CleanupOnFail,
+		historyMax:      cfg.HistoryMax,
 		certs:           newRepoCerts(cfg),
 		createNamespace: cfg.CreateNamespace,
 		skipCrds:        cfg.SkipCrds,
@@ -110,6 +113,9 @@ func (u *Upgrade) Prepare() error {
 	}
 	args = append(args, u.certs.flags()...)
 
+	// always set --history-max since it defaults to non-zero value
+	args = append(args, fmt.Sprintf("--history-max=%d", u.historyMax))
+
 	args = append(args, u.release, u.chart)
 	u.cmd = command(helmBin, args...)
 	u.cmd.Stdout(u.stdout)