Here we will create the common ipsec service configuration. We will use single ike/ipsec policies for all ipsec tunnels. We do that for simplicity, in the real world is not the best practice also not always is applicable.
# enable tunnel-services, we will use it for ipsec/gre
set chassis fpc 0 pic 0 tunnel-services bandwidth 10g
# enable inline-services for ipsec
set chassis fpc 0 pic 0 inline-services bandwidth 10g
# service interface ipsec , any tunnel will used dedicated interface unit
set interfaces si-0/0/0 unit 0 family inet
# common ike policy ike-pol
set services ipsec-vpn ike proposal ike-prop authentication-method pre-shared-keys
set services ipsec-vpn ike proposal ike-prop dh-group group2
set services ipsec-vpn ike proposal ike-prop authentication-algorithm sha1
set services ipsec-vpn ike proposal ike-prop encryption-algorithm aes-128-cbc
set services ipsec-vpn ike policy ike-pol version 2
set services ipsec-vpn ike policy ike-pol proposals ike-prop
# ipsec pre-shared-key "1q2w3e", all tunnels will use the same psk :)
set services ipsec-vpn ike policy ike-pol pre-shared-key ascii-text "$9$AI04p1RhSeMLxlKoJGDmP"
set services ipsec-vpn establish-tunnels immediately
# common ipsec policy ipsec-pol
set services ipsec-vpn ipsec proposal ipsec-prop protocol esp
set services ipsec-vpn ipsec proposal ipsec-prop authentication-algorithm hmac-sha1-96
set services ipsec-vpn ipsec proposal ipsec-prop encryption-algorithm aes-128-cbc
set services ipsec-vpn ipsec policy ipsec-pol proposals ipsec-prop