Allow configuration from env (#15)

Author: Mario Macias

cmd/netobserv-ebpf-agent.go

@@ -4,52 +4,32 @@ package main
 
 import (
 	"context"
-	"flag"
+	"fmt"
 	"os"
 	"os/signal"
 	"syscall"
-	"time"
 
-	"github.com/netobserv/netobserv-ebpf-agent/pkg/agent"
+	"github.com/caarlos0/env/v6"
 	"github.com/sirupsen/logrus"
-)
 
-// TODO: make configurable. NETOBSERV-201
-const (
-	maxStoredFlowEntries      = 1000
-	maxFlowEvictionPeriod     = 5 * time.Second
-	communicationBufferLength = 20
+	"github.com/netobserv/netobserv-ebpf-agent/pkg/agent"
 )
 
 func main() {
-	flag.Parse()
-
-	logrus.SetLevel(logrus.DebugLevel)
-	// temporary hack until NETOBSERV-201
-	flowsTargetHost := os.Getenv("FLOWS_TARGET_HOST")
-	if flowsTargetHost == "" {
-		panic("expecting a collector target host in the FLOWS_TARGET_HOST env var")
+	logrus.Infof("starting NetObserv eBPF Agent")
+	config := agent.Config{}
+	if err := env.Parse(&config); err != nil {
+		logrus.WithError(err).Fatal("can't load configuration from environment")
 	}
-	flowsTargetPort := os.Getenv("FLOWS_TARGET_PORT")
-	if flowsTargetPort == "" {
-		panic("expecting a collector target port in the FLOWS_TARGET_PORT env var")
+	if config.Verbose {
+		logrus.SetLevel(logrus.DebugLevel)
 	}
-	logrus.WithFields(logrus.Fields{
-		"FLOWS_TARGET_HOST": flowsTargetHost,
-		"FLOWS_TARGET_PORT": flowsTargetPort,
-	}).Infof("Starting eBFP flows' agent")
 
-	flowsTarget := flowsTargetHost + ":" + flowsTargetPort
+	logrus.WithField("configuration", fmt.Sprintf("%#v", config)).Debugf("configuration loaded")
 
-	flowsAgent, err := agent.FlowsAgent(&agent.Config{
-		FlowsTarget:        flowsTarget,
-		ExcludeIfaces:      []string{"lo"},
-		BuffersLen:         communicationBufferLength,
-		CacheMaxFlows:      maxStoredFlowEntries,
-		CacheActiveTimeout: maxFlowEvictionPeriod,
-	})
+	flowsAgent, err := agent.FlowsAgent(&config)
 	if err != nil {
-		logrus.WithError(err).Fatal("can't instantiate netobserv-ebpf-agent")
+		logrus.WithError(err).Fatal("can't instantiate NetObserv eBPF Agent")
 	}
 
 	logrus.Infof("push CTRL+C or send SIGTERM to interrupt execution")

go.mod

@@ -3,6 +3,7 @@ module github.com/netobserv/netobserv-ebpf-agent
 go 1.17
 
 require (
+	github.com/caarlos0/env/v6 v6.9.1
 	github.com/cilium/ebpf v0.8.1
 	github.com/mariomac/guara v0.0.0-20220321135847-54b7fb6a8657
 	github.com/netobserv/gopipes v0.1.1
@@ -11,17 +12,20 @@ require (
 	github.com/stretchr/testify v1.7.1
 	github.com/vishvananda/netlink v1.1.0
 	google.golang.org/grpc v1.45.0
-	google.golang.org/protobuf v1.27.1
+	google.golang.org/protobuf v1.28.0
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/google/go-cmp v0.5.7 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df // indirect
-	golang.org/x/net v0.0.0-20200822124328-c89045814202 // indirect
-	golang.org/x/sys v0.0.0-20210906170528-6f6e22806c34 // indirect
-	golang.org/x/text v0.3.0 // indirect
-	google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+	golang.org/x/net v0.0.0-20220412020605-290c469a71a5 // indirect
+	golang.org/x/sys v0.0.0-20220412211240-33da011f77ad // indirect
+	golang.org/x/text v0.3.7 // indirect
+	golang.org/x/xerrors v0.0.0-20220411194840-2f41105eb62f // indirect
+	google.golang.org/genproto v0.0.0-20220407144326-9054f6ed7bac // indirect
+	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -2,6 +2,8 @@ cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMT
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
+github.com/caarlos0/env/v6 v6.9.1 h1:zOkkjM0F6ltnQ5eBX6IPI41UP/KDGEK7rRPwGCNos8k=
+github.com/caarlos0/env/v6 v6.9.1/go.mod h1:hvp/ryKXKipEkcuYjs9mI4bBCg+UI0Yhgm5Zu0ddvwc=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cilium/ebpf v0.8.1 h1:bLSSEbBLqGPXxls55pGr5qWZaTqcmfDJHhou7t254ao=
@@ -48,8 +50,9 @@ github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMyw
 github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
+github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
 github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
@@ -96,8 +99,10 @@ golang.org/x/net v0.0.0-20190108225652-1e06a53dbb7e/go.mod h1:mL1N/T3taQHkDXs73r
 golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20200822124328-c89045814202 h1:VvcQYSHwXgi7W+TpUR6A9g6Up98WAHf3f/ulnJ62IyA=
 golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
+golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
+golang.org/x/net v0.0.0-20220412020605-290c469a71a5 h1:bRb386wvrE+oBNdF1d/Xh9mQrfQ4ecYhW5qJ5GvTGT4=
+golang.org/x/net v0.0.0-20220412020605-290c469a71a5/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -110,24 +115,38 @@ golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210906170528-6f6e22806c34 h1:GkvMjFtXUmahfDtashnc1mnrCtuBVcwse5QV2lUk/tI=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210906170528-6f6e22806c34/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
+golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220412211240-33da011f77ad h1:ntjMns5wyP/fN65tdBD4g8J5w8n015+iIIs9rtjXkY0=
+golang.org/x/sys v0.0.0-20220412211240-33da011f77ad/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.5/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20220411194840-2f41105eb62f h1:GGU+dLjvlC3qDwqYgL6UgRmHXhOOgns0bZu2Ty5mm6U=
+golang.org/x/xerrors v0.0.0-20220411194840-2f41105eb62f/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
 google.golang.org/genproto v0.0.0-20190819201941-24fa4b261c55/go.mod h1:DMBHOl98Agz4BDEuKkezgsaosCRResVns1a3J2ZsMNc=
 google.golang.org/genproto v0.0.0-20200513103714-09dca8ec2884/go.mod h1:55QSHmfGQM9UVYDPBsyGGes0y52j32PQ3BqQfXhyH3c=
-google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013 h1:+kGHl1aib/qcwaRi1CbqBZ1rk19r85MNUf8HaBghugY=
 google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013/go.mod h1:NbSheEEYHJ7i3ixzK3sjbqSGDJWnxyFXZblF3eUsNvo=
+google.golang.org/genproto v0.0.0-20220407144326-9054f6ed7bac h1:qSNTkEN+L2mvWcLgJOR+8bdHX9rN/IdU3A1Ghpfb1Rg=
+google.golang.org/genproto v0.0.0-20220407144326-9054f6ed7bac/go.mod h1:8w6bsBMX6yCPbAVTeqQHvzxW0EIFigd5lZyahWgyfDo=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.23.0/go.mod h1:Y5yQAOtifL1yxbo5wqy6BxZv8vAUGQwXBOALyacEbxg=
 google.golang.org/grpc v1.25.1/go.mod h1:c3i+UQWmh7LiEpx4sFZnkU36qjEYZ0imhYfXVyQciAY=
@@ -147,15 +166,17 @@ google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpAD
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
-google.golang.org/protobuf v1.27.1 h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
-google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.28.0 h1:w43yiav+6bVFTBQFZX0r7ipe9JQ1QsbMgHwbBziscLw=
+google.golang.org/protobuf v1.28.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.3/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=

pkg/agent/agent.go

@@ -2,6 +2,8 @@ package agent
 
 import (
 	"context"
+	"fmt"
+	"net"
 
 	"github.com/netobserv/gopipes/pkg/node"
 	"github.com/netobserv/netobserv-ebpf-agent/pkg/ebpf"
@@ -34,22 +36,25 @@ type flowExporter func(in <-chan []*flow.Record)
 // FlowsAgent instantiates a new agent, given a configuration.
 func FlowsAgent(cfg *Config) (*Flows, error) {
 	alog.Info("initializing Flows agent")
-	interfaces, err := getInterfaces(cfg)
+	interfaces, err := getInterfaces(cfg, net.Interfaces)
 	if err != nil {
 		return nil, err
 	}
 	tracers := map[string]flowTracer{}
 	for iface := range interfaces {
 		tracers[iface] = ebpf.NewFlowTracer(iface)
 	}
-	grpcExporter, err := exporter.StartGRPCProto(cfg.FlowsTarget)
+	target := fmt.Sprintf("%s:%d", cfg.TargetHost, cfg.TargetPort)
+	grpcExporter, err := exporter.StartGRPCProto(target)
 	if err != nil {
 		return nil, err
 	}
 	return &Flows{
-		tracers:   tracers,
-		accounter: flow.NewAccounter(cfg.CacheMaxFlows, cfg.BuffersLen, cfg.CacheActiveTimeout),
-		exporter:  grpcExporter.ExportFlows,
+		tracers: tracers,
+		accounter: flow.NewAccounter(cfg.CacheMaxFlows,
+			cfg.BuffersLength,
+			cfg.CacheActiveTimeout),
+		exporter: grpcExporter.ExportFlows,
 	}, nil
 }
 

pkg/agent/agent_test.go

@@ -2,7 +2,6 @@ package agent
 
 import (
 	"context"
-	"fmt"
 	"testing"
 	"time"
 
@@ -27,11 +26,12 @@ func TestFlowsAgent(t *testing.T) {
 
 	// GIVEN a flows agent
 	flowsAgent, err := FlowsAgent(&Config{
-		FlowsTarget:        fmt.Sprintf("127.0.0.1:%d", port),
+		TargetHost:         "127.0.0.1",
+		TargetPort:         port,
 		Verbose:            true,
 		CacheMaxFlows:      1,
 		CacheActiveTimeout: 5 * time.Second,
-		BuffersLen:         10,
+		BuffersLength:      10,
 	})
 	require.NoError(t, err)
 	// replacing the real eBPF tracer (requires running as root in kernel space)

pkg/agent/config.go

@@ -1,53 +1,91 @@
 package agent
 
 import (
+	"fmt"
 	"net"
+	"regexp"
+	"strings"
 	"time"
 )
 
-// TODO: NETOBSERV-201: fill from CLI and env
 type Config struct {
-	// FlowsTarget is the host:port target of the Flow's collector
-	FlowsTarget string
-	// Ifaces contains the interface names where flow traces will be attached. If empty, the agent
-	// will fetch all the interfaces in the system, excepting the ones listed in ExcludeIfaces
-	Ifaces []string
-	// ExcludeIfaces contains the interface names that will be excluded from flow tracing. Default:
-	// "lo" (loopback)
-	ExcludeIfaces []string
-	// BuffersLen establishes the length of communication channels between the different processing
+	// TargetHost is the host name or IP of the target Flow collector
+	TargetHost string `env:"FLOWS_TARGET_HOST,notEmpty"`
+	// TargetHost is the port the target Flow collector
+	TargetPort int `env:"FLOWS_TARGET_PORT,notEmpty"`
+	// Interfaces contains the interface names from where flows will be collected. If empty, the agent
+	// will fetch all the interfaces in the system, excepting the ones listed in ExcludeInterfaces.
+	// If an entry is enclosed by slashes (e.g. `/br-/`), it will match as regular expression,
+	// otherwise it will be matched as a case-sensitive string.
+	Interfaces []string `env:"INTERFACES" envSeparator:","`
+	// ExcludeInterfaces contains the interface names that will be excluded from flow tracing. Default:
+	// "lo" (loopback).
+	// If an entry is enclosed by slashes (e.g. `/br-/`), it will match as regular expression,
+	// otherwise it will be matched as a case-sensitive string.
+	ExcludeInterfaces []string `env:"EXCLUDE_INTERFACES" envSeparator:"," envDefault:"lo"`
+	// BuffersLength establishes the length of communication channels between the different processing
 	// stages
-	BuffersLen int
+	BuffersLength int `env:"BUFFERS_LENGTH" envDefault:"50"`
 	// CacheMaxFlows specifies how many flows can be accumulated in the accounting cache before
 	// being flushing the cache for its later export
-	CacheMaxFlows int
+	CacheMaxFlows int `env:"CACHE_MAX_FLOWS" envDefault:"1000"`
 	// CacheActiveTimeout specifies the maximum duration in which a flow is kept in the accounting
 	// cache before being flushed for its later export
-	CacheActiveTimeout time.Duration
-	// Verbose mode
-	Verbose bool
+	CacheActiveTimeout time.Duration `env:"CACHE_ACTIVE_TIMEOUT" envDefault:"5s"`
+	// Verbose logs mode
+	Verbose bool `env:"VERBOSE" envDefault:"false"`
 }
 
-// TODO: Ifaces and ExcludeIfaces should admit regexpes e.g. "exclude all the /^br-/ interfaces"
-func getInterfaces(cfg *Config) (map[string]struct{}, error) {
+func getInterfaces(cfg *Config, interfaces func() ([]net.Interface, error)) (map[string]struct{}, error) {
 	// get interfaces from configuration or acquire them from the system
-	ifaces := map[string]struct{}{}
-	if cfg.Ifaces != nil {
-		for _, iface := range cfg.Ifaces {
-			ifaces[iface] = struct{}{}
-		}
-		return ifaces, nil
-	}
-	nifaces, err := net.Interfaces()
+	actual, err := interfaces()
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("can't get network interfaces: %w", err)
 	}
-	for _, iface := range nifaces {
-		ifaces[iface.Name] = struct{}{}
+	accepted := map[string]struct{}{}
+
+	// Accept only defined interfaces, or all if the interfaces section is not defined
+	if len(cfg.Interfaces) > 0 {
+		for _, definition := range cfg.Interfaces {
+			for _, iface := range actual {
+				if m, err := isMatch(iface.Name, definition); err != nil {
+					return nil, fmt.Errorf("wrong definition of interface: %w", err)
+				} else if m {
+					accepted[iface.Name] = struct{}{}
+				}
+			}
+		}
+	} else {
+		for _, iface := range actual {
+			accepted[iface.Name] = struct{}{}
+		}
 	}
+
 	// exclude interfaces
-	for _, iface := range cfg.ExcludeIfaces {
-		delete(ifaces, iface)
+	for _, definition := range cfg.ExcludeInterfaces {
+		for iface := range accepted {
+			if m, err := isMatch(iface, definition); err != nil {
+				return nil, fmt.Errorf("wrong definition of excluded interfaces: %w", err)
+			} else if m {
+				delete(accepted, iface)
+			}
+		}
+	}
+	return accepted, nil
+}
+
+func isMatch(iface, definition string) (bool, error) {
+	var isRegexp = regexp.MustCompile("^/(.*)/$")
+	definition = strings.Trim(definition, " ")
+
+	// the user defined a /regexp/ between slashes: check if matches
+	if sm := isRegexp.FindStringSubmatch(definition); len(sm) > 0 {
+		m, err := regexp.MatchString(sm[1], iface)
+		if err != nil {
+			return false, fmt.Errorf("wrong pattern %s: %w", definition, err)
+		}
+		return m, nil
 	}
-	return ifaces, nil
+	// the user defined a plain string: check exact match
+	return iface == definition, nil
 }